LIX issues Area Forecast Discussion (AFD) at Jul 20, 1:43 PM CDT ...New SHORT TERM, LONG TERM, AVIATION, MARINE...
748
FXUS64 KLIX 201843
AFDLIX
Area Forecast Discussion
National Weather Service New Orleans LA
143 PM CDT Sun Jul 20 2025
...New SHORT TERM, LONG TERM, AVIATION, MARINE...
.SHORT TERM...
(This evening through Monday night)
Issued at 135 PM CDT Sun Jul 20 2025
The weak upper low that was over the local area at the end of last
week is now over Texas with mid level ridging off the coast of
Plaquemines Parish. At the surface, high pressure is centered over
the Gulf somewhere south of Pensacola. Scattered cumulus were
noted on satellite, and there may be one or two showers out there,
but the overwhelming majority of the area is, and will, be dry
this afternoon. Temperatures at early afternoon range from the
upper 80s to mid 90s with heat index values around 105.
The upper ridge will continue to drift west and northwest over the
next 36 hours, and cover most of the lower Mississippi River
Valley by tomorrow night. Cannot entirely rule out isolated storms
this afternoon and tomorrow afternoon, but most areas will remain
dry, and any storms that do develop should dissipate by sunset.
Main concern is going to be the heat. While conditions are
borderline for an advisory today, high temperatures tomorrow look
to be in the mid 90s areawide, and a few spots could reach 97F or
so. Dew points look to be in the same general range as today, mid
and upper 70s, so heat index values could actually be a touch
higher tomorrow. Have already pre-emptively issued a Heat Advisory
for tomorrow for all of the area except the lower portions of the
southeast Louisiana coastal parishes. The same areas as today's
advisory.
&&
.LONG TERM...
(Tuesday through Saturday night)
Issued at 135 PM CDT Sun Jul 20 2025
The upper ridge will drift northward Tuesday and be centered near
Memphis Tuesday, before moving eastward later in the week. This
will allow an easterly wave to move across the northern Gulf
Wednesday and Thursday. A northern stream shortwave could push a
frontal boundary about as far south as Interstate 20 next weekend.
Similar to Monday, any thunderstorm threat will remain very
isolated, with most areas remaining dry. If there is a focus for
convection on Tuesday, it would be lake/sea breeze boundaries.
High temperatures Tuesday could actually be a degree or two higher
than tomorrow, with some guidance indicating upper 90s for highs.
With a northerly component to surface winds on Tuesday, it is one
of those situations where the "hot spot" could actually the Pearl
and Pascagoula River Basins (Bogalusa, Slidell, Mississippi
coastal cities) if the sea breeze kicks in late or not at all and
no storms develop. In fact the MAVPQL (GFS based MOS for
Pascagoula) gives 101 for Tuesday. Heat Advisories almost certain
to be issued for Tuesday, and later shifts may need to consider an
Extreme Heat Warning for portions of the area.
As the easterly wave moves across the northern Gulf Wednesday and
Thursday, moisture levels will again be on the increase with
precipitable water values jumping from the 1.5 to 1.7 inch range
Tuesday to well in excess of 2 inches by late Wednesday afternoon
into Thursday. Still some question as to how quickly the moisture
spreads in on Wednesday, and how far north. Convective initiation
may hold off until late afternoon, which may necessitate a Heat
Advisory for portions or most of the area.
Thursday into next weekend will likely see daily development of
showers and thunderstorms across much of the area. The additional
cloud cover and precipitation should hold high temperatures much
closer to "normal" for late July, while overnight lows will be in
the mid and upper 70s.
&&
.AVIATION...
(18Z TAFS)
Issued at 135 PM CDT Sun Jul 20 2025
Only very isolated TSRA so far this afternoon, and threat was too
low to mention in most terminals, other than VCTS at KHUM. Won't
rule out 1 or 2 amendments this afternoon. Overnight should see
VFR conditions, and don't expect a repeat from this morning of
very low conditions at KMCB. Cumulus development tomorrow should
be even less than today.
&&
.MARINE...
Issued at 135 PM CDT Sun Jul 20 2025
Main concerns for marine operations this week will be the threat
of thunderstorms, as the general pressure gradient is expected to
remain rather weak. Thunderstorm development is expected to remain
fairly limited over the local waters until about Wednesday, when
areal coverage increases significantly. The second half of the
week will see multiple rounds of storms that will be capable of
producing locally higher winds and seas.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 73 95 73 96 / 0 0 0 10
BTR 76 94 75 95 / 0 10 0 10
ASD 75 94 75 96 / 10 10 0 20
MSY 78 94 78 96 / 10 20 0 20
GPT 77 94 78 96 / 0 10 0 20
PQL 76 95 75 97 / 0 10 10 30
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Heat Advisory until 7 PM CDT this evening for LAZ034>037-039-
046>048-056>060-064-065-071-076>090.
Heat Advisory from 10 AM to 7 PM CDT Monday for LAZ034>037-039-
046>048-056>060-064-065-071-076>090.
GM...None.
MS...Heat Advisory until 7 PM CDT this evening for MSZ068>071-077-
083>088.
Heat Advisory from 10 AM to 7 PM CDT Monday for MSZ068>071-077-
083>088.
GM...None.
&&
$$
SHORT TERM...RW
LONG TERM....RW
AVIATION...RW
MARINE...RW
Source: LIX issues Area Forecast Discussion (AFD) at Jul 20, 1:43 PM CDT ...New SHORT TERM, LONG TERM, AVIATION, MARINE... (https://mesonet.agron.iastate.edu/p.php?pid=202507201843-KLIX-FXUS64-AFDLIX)
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